This invention relates to an apparatus for carrying out by automatic control the process of treating waste gases containing nitrogen oxides (NO.sub.x) and sulfur dioxide (SO.sub.2) by irradiation and with the addition of ammonia (NH.sub.3). An electron beam accelerator is generally used as a radiation source in the practice of this process.
Among the known waste gas purification processes which have been developed heretofore, there is one in which NH.sub.3 is added to the waste gas containing NO.sub.x and SO.sub.2 and the same gas is irradiated with electron beams to thereby convert NO.sub.x and SO.sub.2 contained therein as small amounts of toxic gaseous components into minute solid particles which can be removed from the waste gas by a dust collector placed in the later stage. This process is carried out by introducing waste gas to which NH.sub.3 has been added to a reactor, where the waste gas is irradiated through the "window for irradiation" of the reactor to convert the small amounts of toxic gaseous components to aerosol and then carrying the thus irradiated waste gas into a dust collector such as an electrostatic precipitator to thereby separate said aerosol.
For the successful practical operation of this process, it is required to control the amount of NH.sub.3 to be added to the waste gas and also to control the dose rate of electron beams so that both said amount and said dose rate may meet the concentrations, which vary at every moment, of NO.sub.x and SO.sub.2 of the waste gas to be treated.
Namely, for the continuous practical operation of this type of process, it is important to maintain the respective concentrations of NO.sub.x, SO.sub.2 and NH.sub.3 of the treated waste gas within a certain limited range and thereby to minimize the consumption of NH.sub.3 and the output of electron beams.